创建型模式 - 单例模式

一个类只有一个实例

使用场景

1. 数据库连接

Demo

"""
单例模式
"""
class SingleObject:
    __instance = None
    def __new__(cls, *args, **kwargs):
        if cls.__instance is None:
            cls.__instance = super().__new__(cls)
        return cls.__instance
    def __init__(self, name):
        self.name = name
if __name__ == '__main__':
    a = SingleObject("ming")
    print(a.name)
    b = SingleObject("uzi")
    print(b.name)
    print(a.name)
    print(a is b)